In recent years, a device that detects an obstacle such as a pedestrian, a vehicle, or a guardrail using a stereo camera and issues an alert or performs break assist is practically used.
However, when a disparity by the stereo camera is calculated, it is probably difficult to obtain the disparity from a plane which does not a pattern or a wall on which the identical stripes are uniformly drawn, and in this case, it is difficult to prevent the collision with the obstacle.
In order to solve the above-mentioned problem, for example, as disclosed in PTL 1, a method that, when a clutch mechanism is operated at a rear side, pattern light is irradiated at a rear side of the vehicle to obtain the disparity from a wall of a garage which does not have a pattern is disclosed.